T2.8 vs F2.8 [film/video lenses vs photography lenses]
whats the difference? do the letters just signify what they are?
like T2.8 and F2.8, do they both gather the same amount of light?
StructuredAmazing Senior Member ![]() 603 posts Joined Jul 2010 More info       | Nov 15, 2010 23:01 | #1 T2.8 vs F2.8 [film/video lenses vs photography lenses] "Yea, though I walk through the valley of the shadow of death, I will fear no evil"
LOG IN TO REPLY |
phreeky Goldmember 3,471 posts Likes: 2 Joined Oct 2007 Location: Australia More info       | Nov 15, 2010 23:11 | #2 My understanding is that the F-stop is the theoretical/true aperture, and the T-stop instead takes all light loss (i.e. from optical elements) into account. A T-stop is the figure you want to use for exact exposure information.
LOG IN TO REPLY |
JeffreyG "my bits and pieces are all hard" ![]() More info       | Nov 16, 2010 05:38 | #3 F-stop is the ratio of the aperture to the focal length. T-stop is the same and includes an offset to account for the amount of light lost in the lens due to transmission losses. My personal stuff:http://www.flickr.com/photos/jngirbach/sets/
LOG IN TO REPLY |
alemerson Member 56 posts Joined May 2010 More info       | Nov 16, 2010 12:36 | #4 5D Mark II | 16-35L II | 24-105L | 35L | 50 f/1.4
LOG IN TO REPLY |
JPM Photography Senior Member ![]() 603 posts Joined Apr 2008 More info       | Nov 16, 2010 13:28 | #5 http://en.wikipedia.org/wiki/F-number#T-stops 60D gripped, T2i gripped, Tokina 12-24 f/4, Pentax SMC 50 f/1.4, Nikon Standard Speed Set: 24, 35, 85, 105, 135, 180, Canon 580ex, Calumet Genesis 200
LOG IN TO REPLY |
RaZe42 Senior Member ![]() 518 posts Likes: 1 Joined Feb 2010 Location: Finland More info       | Nov 16, 2010 13:58 | #6 DxOmark has the t-stops of the lenses they've tested listed. Some people are quite skeptical towards DxO, but things like that should be quite easy to measure, so the results should be reliable. eg the 24-205 f/4 is T5.1, the 24-70 f/2.8 is T3.4. Gear: Canon 5D Mk II | Olympus 21/3.5 | Zeiss Distagon 35/2 | Sigma 50/1.4 ASPH | Samyang 85/1.4 ASPH | Canon 100/2.8 L Macro
LOG IN TO REPLY |
JeffreyG "my bits and pieces are all hard" ![]() More info       | Nov 16, 2010 16:00 | #7 RaZe42 wrote in post #11295361 ![]() DxOmark has the t-stops of the lenses they've tested listed. Some people are quite skeptical towards DxO, but things like that should be quite easy to measure, so the results should be reliable. eg the 24-205 f/4 is T5.1, the 24-70 f/2.8 is T3.4. How do they account for vignetting? Are they measuring the T-stop at the center of the frame or as an average value? My personal stuff:http://www.flickr.com/photos/jngirbach/sets/
LOG IN TO REPLY |
phreeky Goldmember 3,471 posts Likes: 2 Joined Oct 2007 Location: Australia More info       | Nov 16, 2010 16:10 | #8 JeffreyG wrote in post #11296093 ![]() How do they account for vignetting? Are they measuring the T-stop at the center of the frame or as an average value? It SHOULD be across the frame. I have seen another website that had the T-stop of a bunch of lenses but cannot remember what it was.
LOG IN TO REPLY |
![]() | x 1600 |
y 1600 |
Log in |
| ||
Latest registered member is Nidge 710 guests, 392 members online Simultaneous users record so far is 6430, that happened on Dec 03, 2017 |